1. Field of the Disclosure
The present disclosure generally relates to a method of controlling communication modes for a wireless entity and a user equipment, and a communication system using the same method.
2. Description of Related Art
Recently, deploying more small cells such as Pico cell, Remote Radio Header and etc. and utilizing all spectrum resources are keys to meet the anticipated 1000× system capacity for satisfying the increase of data traffic. Although licensed spectrum is the foundation, bandwidth-rich unlicensed spectrum around 5 GHz band can be used to effectively augment the system capacity. Bringing Long Term Evolution (LTE) Advanced to unlicensed spectrum could be an idea with immense benefits as it involves leveraging large number of small cells that operators may plan to deploy and aggregating unlicensed spectrum with the licensed spectrum for LTE Advanced. The existing core network can be used without significant modifications. In essence, the whole system may work as a unified LTE network to efficiently leverage both licensed and unlicensed spectrum bands. To implement such idea, a Studying Group has been initiated at the 3GPP standard organization to discuss potential uses of the integration between LTE and unlicensed LTE. From an operator perspective, a unified air-interface of LTE over the licensed and unlicensed band is attractive because of unified authentication and security management, service quality guarantee, Operations support systems (OSS) and radio resource management, etc. Furthermore, a close coupling of small cells operating on the unlicensed spectrum with licensed macro-cells could simplify joint operations of both spectrum types. It is also noted that the macro-cells could provide licensed LTE and unlicensed LTE without any small cell's cooperation. From the user perspective, the joint operations may bring about an enhanced broadband experience which includes higher data rates, seamless use of both licensed and unlicensed bands, higher reliability, better mobility, and more.
One promising solution for LTE over Unlicensed spectrum (LTE-U) under regulations is the operator-controlled non-standalone deployment of LTE-U. The non-standalone LTE-U as depicted in FIG. 1 represents licensed spectrum and unlicensed spectrum were aggregated to provide transmission to the user equipment (UE). The licensed spectrum will serve as primary component carrier (PCC) whereas mobility management, Radio Resource Control (RRC) signaling, and scheduling results would be transmitted over that carrier. Alternatively, unlicensed spectrum serves as secondary component carrier (SCC) whereas the carrier would be used for transmitting some particular data. Under non-standalone LTE-U, the above problems would be simplified since control signaling are available and reliable on PCC and the remaining problems are how to decide when to activate the SCC on unlicensed spectrum. Notice that it is also possible to provide control signaling on SCC (i.e., LTE-U), but eNB shall guarantee the reliability and shall notify UE the corresponding operation.
After introducing LTE-U, an operator could either deploy a Wi-Fi access point (AP) or a LTE-U small cell to provide traffic offloading with Macro cell (operated at licensed spectrum). Unfortunately, those two Radio Access Technologies (RATs) might contention with each other if the operator deploys both of them in a particular area upon the same unlicensed spectrum and consequently, the performance might be degraded. Therefore, it requires a coordination mechanism or a new architecture to let the operator could utilize the unlicensed spectrum in efficient way.